Sequence of events during the last deglaciation in Southern Ocean sediments and Antarctic ice cores

• Published in: Paleoceanography
• Main Authors: Shemesh, A., Hodell, D., Crosta, X., Kanfoush, S., Charles, C., Guilderson, T.
• Other Authors: Department of Earth and Planetary Sciences Rehovot, Weizmann Institute of Science Rehovot, Israël, University of Florida Gainesville (UF), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Syracuse University, University of California San Diego (UC San Diego), University of California (UC), Lawrence Livermore National Laboratory (LLNL)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2002
• Subjects: biogenic opal; stable isotopes; diatoms; IRD; last glacial; Southern Ocean; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; Antarctic; Antarc*; ice core; Sea ice
• Online Access: https://hal.science/hal-02105702; https://hal.science/hal-02105702/document; https://hal.science/hal-02105702/file/Shemesh_Paleocean2002.pdf; https://doi.org/10.1029/2000PA000599

International audience The last glacial to interglacial transition was studied using down core records of stable isotopes in diatoms and foraminifera as well as surface water temperature, sea ice extent, and ice-rafted debris (IRD) concentrations from a piston core retrieved from the Atlantic sector of the Southern Ocean. Sea ice is the first variable to change during the last deglaciation, followed by nutrient proxies and sea surface temperature. This sequence of events is independent of the age model adopted for the core. The comparison of the marine records to Antarctic ice CO 2 variation depends on the age model as 14 C determinations cannot be obtained for the time interval of 29.5-14.5 ka. Assuming a constant sedimentation rate for this interval, our data suggest that sea ice and nutrient changes at about 19 ka B.P. lead the increase in atmospheric pCO 2 by approximately 2000 years. Our diatom-based sea ice record is in phase with the sodium record of the Vostok ice core, which is related to sea ice cover and similarly leads the increase in atmospheric CO 2. If gas exchange played a major role in determining glacial to interglacial CO 2 variations, then a delay mechanism of a few thousand years is needed to explain the observed sequence of events. Otherwise, the main cause of atmospheric pCO 2 change must be sought elsewhere, rather than in the Southern Ocean.